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Settings
Below the device list there are several fields through which some general settings can be
configured:
Interval
Defines the interval in milliseconds in which all Modbus values will be read/written; Note that if the
interval is too short to read/write all values, a warning message will be shown on the event log. In this
case you should increase the interval. In the worst case reading/writing a value may take twice the
time specified for the timeout (see below), i.e. when the driver has to connect to a Modbus TCP device
(first timeout) before reading/writing the value (second timeout).
Timeout
Defines the maximum time in milliseconds to wait for the reply of a device when reading/writing one
of its values or when connecting to a Modbus TCP device.
Additionally the communication parameters for Modbus RTU can be set. If your Edge
gateway device features several serial interfaces those can be configured separately.
Enable RTU
Generally enables Modbus RTU.
Mode
Defines the mode for Modbus RTU. There are three possible options:
•
RS232 with RTS/CTS flow control
•
RS232 without flow control
•
RS485
Baud rate
Defines the baud rate for Modbus RTU.
Parity
Defines the parity (and stop bits) for Modbus RTU. There are four possible options:
•
None (2 stop bits)
•
Odd
•
Even
•
None (1 stop bit) - This option is illegal according to the Modbus specification, but still some
slaves use it.
Minimum
silent time
between
frames
Defines the minimum time for which there has to be silence on the bus between two frames. The
Modbus RTU driver calculates the silence time depending on the baud rate. Normally this should be
sufficient. However you can use this setting to increase the silent time. If the time you configure here
is less than the calculated time, your setting will be ignored.
Event Log Messages
The following section describes the messages that the Modbus driver may log to the Event Log.
All Messages are prefixed with the text
Modbus driver:
.
•
Connected to TCP device at
<IP address>
:
<port>
.
The driver successfully connected to the Modbus TCP server with the given IP address and
port. This message will only be shown if the driver failed to connect to the same server
before.
•
Read/wrote from/to TCP device at
<IP address>
:
<port>
(unit:
<unit identifier>
, function
code:
<function code>
, address:
<address>
, quantity:
<quantity>
)
The driver successfully read/wrote a value from/to the Modbus TCP server with the given IP
address and port. The corresponding value is identified by the Modbus function code used
to read/write it, its address (starting from 0) and the quantity of registers/coils. This
message will only be shown if the driver failed to read/write the same value before.
•
Read/wrote from/to RTU device
<serial port>
:
<device address>
(function code:
<function
code>
, address:
<value address>
, quantity:
<quantity>
)
The driver successfully read/wrote a value from/to the Modbus RTU slave with the given
address. The corresponding value is identified by the Modbus function code used to read/
write it, its address (starting from 0) and the quantity of registers/coils. This message will
only be shown if the driver failed to read/write the same value before.
Anybus Edge Gateway Reference Guide
SCM-1202-154 1.0 en-US
